US20220324557A1 - Rotary aircraft hybrid rotor mast - Google Patents
Rotary aircraft hybrid rotor mast Download PDFInfo
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- US20220324557A1 US20220324557A1 US17/580,392 US202217580392A US2022324557A1 US 20220324557 A1 US20220324557 A1 US 20220324557A1 US 202217580392 A US202217580392 A US 202217580392A US 2022324557 A1 US2022324557 A1 US 2022324557A1
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- fitting
- shaft body
- shaft assembly
- shaft
- longitudinal axis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C27/00—Rotorcraft; Rotors peculiar thereto
- B64C27/04—Helicopters
- B64C27/12—Rotor drives
- B64C27/14—Direct drive between power plant and rotor hub
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C27/00—Rotorcraft; Rotors peculiar thereto
- B64C27/04—Helicopters
- B64C27/12—Rotor drives
Definitions
- the present disclosure is directed generally to rotor masts for rotary aircraft, and associated systems and methods.
- Rotor masts transfer rotation (torque) from a transmission or engine to an aircraft rotor hub to drive the aircraft rotor, which produces thrust.
- Conventional rotor masts consist of metal components that contribute to the overall weight of the aircraft and reduce efficiency. All-metal rotor masts are also susceptible to corrosion and fatigue. Accordingly, there is a desire for durable rotor masts with reduced weight. Aspects of the present technology are generally directed to addressing these challenges.
- Representative embodiments of the present technology include a shaft assembly for transferring rotation from a power source to a hub.
- the shaft assembly includes a shaft body having composite material, the shaft body extending along a longitudinal axis, and a fitting attached to the shaft body, the fitting having an interior opening positioned to receive the shaft body.
- a cross-section of the interior opening taken perpendicular to the longitudinal axis comprises a non-circular perimeter.
- an aerospace system including an aerospace vehicle, a power source carried by the aerospace vehicle, a rotor assembly including a hub and one or more (such as two or more) rotor blades supported by the hub, and a shaft assembly for transferring rotation from the power source to the hub, the shaft assembly being configured in accordance with embodiments of the present technology.
- a fitting for a rotatable shaft assembly having an interior opening positioned to receive a shaft body, wherein the interior opening includes a converging portion, a diverging portion, and a non-circular portion positioned between the converging portion and the diverging portion.
- Embodiments of the present technology provide rotor masts and other shaft assemblies with improved weight and durability characteristics, among other advantages.
- FIG. 1 is a schematic illustration of a rotary aircraft or rotorcraft implementing a rotor mast configured in accordance with embodiments of the present technology.
- FIG. 2 is a partially schematic side view of the rotor mast shown in FIG. 1 , configured in accordance with embodiments of the present technology.
- FIG. 3 is a partially schematic cross-sectional view of the rotor mast shown in FIG. 2 , taken across the line labeled “ FIG. 3 ” indicated in FIG. 2 .
- FIG. 4 is a detailed view of a portion of FIG. 3 .
- FIG. 5 is a schematic cross-sectional view of portions of FIGS. 2, 3 , and/or 4 , as indicated by the “ FIG. 5 ” indicator in FIGS. 2, 3 , and/or 4 .
- the present technology is generally directed to rotor masts for rotary aircraft, and associated systems and methods.
- Various embodiments of the technology will now be described. The following description provides specific details for a thorough understanding and enabling description of these embodiments. One skilled in the art will understand, however, that the invention may be practiced without many of these details. Additionally, conventional or well-known aspects of rotorcraft and composite materials may not be shown or described in detail so as to avoid unnecessarily obscuring the relevant description of the various embodiments. Any of the features described herein may be combined in suitable manners with any of the other features described herein without deviating from the scope of the present technology. Accordingly, embodiments of the present technology may include additional elements, or may exclude some of the elements described below with reference to FIGS. 1-5 , which illustrate examples of the technology.
- FIG. 1 is a schematic illustration of a rotary aircraft or rotorcraft 100 implementing a rotor mast 110 configured in accordance with embodiments of the present technology.
- the rotorcraft 100 may include a vehicle body 120 , a power source 130 carried by the vehicle body 120 , a rotor assembly 140 (which may include a hub 150 supporting one or more rotor blades 160 , such as two or more rotor blades 160 ), and the rotor mast 110 , which transfers rotation (torque) from the power source 130 to the rotor assembly 140 to rotate the rotor assembly 140 to create thrust and/or lift.
- the power source 130 can include an engine, a transmission, and/or other suitable devices or mechanisms for rotating the rotor mast 110 and the rotor assembly 140 .
- the rotorcraft 100 can include features that are conventional to rotorcraft 100 or other aircraft, in addition to implementing aspects of the rotor mast 110 in accordance with embodiments of the present technology.
- FIG. 2 is a partially schematic side view of the rotor mast 110 , configured in accordance with embodiments of the present technology.
- the rotor mast 110 includes a shaft body 210 and at least one fitting attached to the shaft body 210 .
- the rotor mast 110 may include a first fitting 220 , a second fitting 230 , and/or an inner race element 240 (which may be called a third fitting), each being attached to the shaft body 210 .
- the first fitting 220 may be configured to connect to the power source 130 (see FIG. 1 ).
- the first fitting 220 may include a gear and/or the first fitting 220 may be connected to a gear, such as a splined drive, a bull gear, a planetary carrier, and/or another gear or plurality of gears, and/or another suitable connection to the power source 130 .
- the second fitting 230 may be configured to connect to the hub 150 (see FIG. 1 ).
- the first and second fittings 220 , 230 may include suitable features for transferring torque, such as splines (some representative splines 250 are schematically illustrated in FIG. 2 ).
- the inner race element 240 may be configured to mate with a bearing surface or other bearing device associated with the rotorcraft 100 , such as a portion of the power source 130 , for supporting the rotor mast 110 in an aligned position while also allowing rotation of the rotor mast 110 .
- the shaft body 210 comprises composite material, such as composite laminate material.
- the shaft body 210 may be formed by suitable composite manufacturing techniques.
- the shaft body 210 may be formed with a fiber placement process.
- the first and second fittings 220 , 230 and/or the inner race element 240 may comprise metal material or another suitable material.
- the rotor mast 110 may be called a hybrid rotor mast because it may include a composite shaft body 210 attached to metal fittings.
- FIG. 3 is a partially schematic cross-sectional view of the rotor mast 110 , taken across the line labeled “ FIG. 3 ” in FIG. 2 .
- the first fitting 220 includes a first fitting interior opening 300 positioned and configured to receive the shaft body 210 .
- the second fitting 230 includes a second fitting interior opening 310 positioned and configured to receive the shaft body 210 .
- the inner race element 240 also includes an inner race opening 320 positioned and configured to receive the shaft body 210 .
- the shaft body 210 may extend through the inner race element 240 and into each of the fittings 220 , 230 . In some embodiments, the shaft body 210 may not extend through the full length of either of the fittings 220 , 230 .
- the shaft body 210 expands outwardly relative to its longitudinal axis x to contour against the inner surfaces of the fittings 220 , 230 , and/or the inner race element 240 .
- the shaft body 210 may also be attached to the fittings 220 , 230 , 240 with an adhesive material 330 positioned in one or more (such as all) of the fittings 220 , 230 , 240 , between the fittings 220 , 230 , 240 and the shaft body 210 .
- the adhesive can include an epoxy film adhesive such as FM 300 or AF 163 , or another adhesive suitable for facilitating bonding between the composite shaft body 210 and the material forming the fittings with shear strength characteristics and other characteristics suitable for use in rotorcraft or otherwise suitable for bonding composite material to metal material.
- the adhesive material 330 it may be preferable to include the adhesive material 330 in order to provide redundancy to the connection between the shaft body 210 and the fitting(s) 220 , 230 , 240 .
- the adhesive material 330 is optional and may be omitted if such redundancy is not required or desired.
- FIG. 4 is a detailed view of a portion of FIG. 3 (as indicated by the “ FIG. 4 ” annotation in FIG. 3 ).
- the adhesive material 330 is not shown in FIG. 4 .
- an interface 400 between the second fitting 230 and the shaft body 210 may be contoured along the longitudinal axis x. Contouring the interface 400 along the longitudinal axis x provides a mechanical lock between the second fitting 230 and the shaft body 210 , which complements the adhesive material 330 .
- the second fitting interior opening 310 may include an inner surface 410 that may be contoured along the longitudinal axis x.
- the interface 400 may be formed by the shaft body 210 being expanded against the inner surface 410 .
- the inner surface 410 may include a first tapered section 420 in which the inner surface 410 converges toward the longitudinal axis x, a second tapered section 440 in which the inner surface 410 diverges away from the longitudinal axis x, and/or a non-tapered section 450 (extending parallel to the longitudinal axis x) positioned between the first and second tapered sections 420 , 440 .
- the first tapered section 420 may be called a converging portion and the second tapered section 440 may be called a diverging portion.
- the non-tapered section 450 may be an apex or transition point rather than a surface extending along the longitudinal axis x.
- the one or more tapered sections 420 , 440 carry axial loads of the rotor mast 110 by resisting movement of the fitting 230 along the longitudinal axis x.
- the first tapered section 420 carries axial loads opposite the positive thrust direction and the second tapered section 440 carries axial loads in the positive thrust direction.
- the contouring of the inner surface 410 also carries moment loads (transverse to the x-axis) against the interface 400 to support moment loads on the overall rotor mast 110 .
- tapered sections 420 , 440 are illustrated and described with regard to FIG. 4 , in some embodiments, more or fewer tapered sections may be implemented, which may entail additional non-tapered sections 450 therebetween. Accordingly, the inner surface 410 may be contoured in other ways to lock the fitting 230 in position along the longitudinal axis x and to lock the fitting 230 against moment loads.
- the interior opening 300 of the first fitting 220 may include a similar configuration as the interior opening 310 of the second fitting 230 .
- the first fitting 220 may include a converging taper, a diverging taper, and/or a non-tapered section between the converging taper and the diverging taper ( FIG. 3 shows tapering of the opening 300 in the first fitting 220 similar to the tapering of the opening 310 in the second fitting 230 ).
- the interface 400 shown in FIG. 4 may be implemented in the first fitting 220 .
- the first fitting 220 may also interface with the shaft body 210 in a manner that facilitates support of axial and moment loads by the rotor mast 110 .
- FIG. 5 is a schematic cross-sectional view of portions of FIGS. 2, 3 , and/or 4 , as indicated by the “ FIG. 5 ” indicator in FIGS. 2, 3, and 4 .
- some or all of the interface 500 between the shaft body 210 and the fittings 220 , 230 , 240 may have a non-circular cross-sectional shape.
- the non-tapered section 450 between the tapered sections 420 , 440 may have a non-circular perimeter.
- a non-tapered section between tapered sections in the first fitting 230 may have a non-circular perimeter.
- An inner perimeter of the inner race element 240 may have a non-circular perimeter.
- the tapered sections of the fittings may have non-circular cross-sectional shapes. In other embodiments, the tapered sections may have circular cross-sectional shapes.
- the shaft body 210 may also have a non-circular cross-sectional shape at the interfaces 500 .
- the engagement of the non-circular cross-sectional shapes of the shaft body 210 and the openings in the fittings facilitates transfer of torque between the shaft body 210 and the fittings.
- the non-circular interfaces 500 (and consequently, the non-circular perimeters of the openings within the fittings) have an elliptical shape.
- the non-circular interfaces 500 may have oval shapes, shapes having one or more lobes, and/or shapes having one or more recesses. Embodiments of the present technology may have other suitable non-circular shapes.
- Rotor masts configured in accordance with embodiments of the present technology may be manufactured with existing manufacturing methods.
- the composite tube (shaft body 210 ) may be laid up on a mandrel (such as an inner mold line mandrel).
- a suitable method for consolidating the laminate material includes fiber placement composite fabrication.
- the composite tube (shaft body 210 ) may then be installed in an outer mold line tool along with the fittings.
- the mandrel may be removed and replaced with a bladder.
- the bladder may apply pressure to creep the composite material outwardly toward the fittings and the tool (i.e., to contour the composite material against the inner surfaces of the fittings 220 , 230 , and/or the inner race element 240 ).
- the fittings may function as mold tooling during the curing process. After curing, the tool may be removed from the completed rotor mast assembly.
- the shaft assembly may include an optional plug element 655 (shown in FIG. 4 , for example) temporarily or permanently positioned in the composite tube (shaft body 210 ) to support the composite tube (shaft body 210 ) during curing.
- the optional plug element 655 may be used to prevent the composite tube 210 from being pulled from the fitting during curing or after curing. However, in some embodiments, the plug element 655 may be omitted.
- Embodiments of the present technology include reduced weight, improved strength, and improved corrosion resistance relative to conventional rotor masts.
- Embodiments of the present technology also provide redundancies in the connection between the composite shaft body 210 and the metal components. For example, torque loads about the x-axis (which rotate the rotor assembly 140 , for example) may be supported by the non-circular interfaces between the shaft body 210 and the fittings 220 , 230 , 240 , with redundancy provided by the adhesive 300 .
- the axial contouring of the interfaces between the shaft body 210 and the fittings supports axial and moment loads.
- the adhesive may further assist the mechanical bond formed by the contouring.
- the rotor mast 110 may include more or fewer fittings or bearing components.
- rotor masts are described, the technology described herein can be used to make other shaft assemblies, including other shaft assemblies for transferring rotation from a power source to a hub, such as propeller shafts for airplanes.
Abstract
Description
- The present application claims priority to U.S. Provisional Patent Application No. 63/164,884, filed Mar. 23, 2021, which is incorporated herein in its entirety by reference.
- The inventions disclosed herein were made with government support under W911W6-13-2-0004 awarded by the United States Army Contracting Command. The government has certain rights in the inventions.
- The present disclosure is directed generally to rotor masts for rotary aircraft, and associated systems and methods.
- Rotor masts transfer rotation (torque) from a transmission or engine to an aircraft rotor hub to drive the aircraft rotor, which produces thrust. Conventional rotor masts consist of metal components that contribute to the overall weight of the aircraft and reduce efficiency. All-metal rotor masts are also susceptible to corrosion and fatigue. Accordingly, there is a desire for durable rotor masts with reduced weight. Aspects of the present technology are generally directed to addressing these challenges.
- Representative embodiments of the present technology include a shaft assembly for transferring rotation from a power source to a hub. In some embodiments, the shaft assembly includes a shaft body having composite material, the shaft body extending along a longitudinal axis, and a fitting attached to the shaft body, the fitting having an interior opening positioned to receive the shaft body. In some embodiments, a cross-section of the interior opening taken perpendicular to the longitudinal axis comprises a non-circular perimeter.
- Other representative aspects include an aerospace system including an aerospace vehicle, a power source carried by the aerospace vehicle, a rotor assembly including a hub and one or more (such as two or more) rotor blades supported by the hub, and a shaft assembly for transferring rotation from the power source to the hub, the shaft assembly being configured in accordance with embodiments of the present technology.
- Other representative aspects include a fitting for a rotatable shaft assembly, the fitting having an interior opening positioned to receive a shaft body, wherein the interior opening includes a converging portion, a diverging portion, and a non-circular portion positioned between the converging portion and the diverging portion.
- Embodiments of the present technology provide rotor masts and other shaft assemblies with improved weight and durability characteristics, among other advantages.
- Other features and advantages will appear hereinafter. The features described herein can be used separately or together, or in various combinations of one or more of them.
- In the drawings, wherein the same reference number indicates the same element throughout the several views:
-
FIG. 1 is a schematic illustration of a rotary aircraft or rotorcraft implementing a rotor mast configured in accordance with embodiments of the present technology. -
FIG. 2 is a partially schematic side view of the rotor mast shown inFIG. 1 , configured in accordance with embodiments of the present technology. -
FIG. 3 is a partially schematic cross-sectional view of the rotor mast shown inFIG. 2 , taken across the line labeled “FIG. 3 ” indicated inFIG. 2 . -
FIG. 4 is a detailed view of a portion ofFIG. 3 . -
FIG. 5 is a schematic cross-sectional view of portions ofFIGS. 2, 3 , and/or 4, as indicated by the “FIG. 5 ” indicator inFIGS. 2, 3 , and/or 4. - The present technology is generally directed to rotor masts for rotary aircraft, and associated systems and methods. Various embodiments of the technology will now be described. The following description provides specific details for a thorough understanding and enabling description of these embodiments. One skilled in the art will understand, however, that the invention may be practiced without many of these details. Additionally, conventional or well-known aspects of rotorcraft and composite materials may not be shown or described in detail so as to avoid unnecessarily obscuring the relevant description of the various embodiments. Any of the features described herein may be combined in suitable manners with any of the other features described herein without deviating from the scope of the present technology. Accordingly, embodiments of the present technology may include additional elements, or may exclude some of the elements described below with reference to
FIGS. 1-5 , which illustrate examples of the technology. - The terminology used in this description is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this detailed description section.
- As used herein, the term “and/or” when used in the phrase “A and/or B” includes A alone, B alone, and both A and B. A similar manner of interpretation applies to the term “and/or” when used in a list of more than two terms. Further, unless otherwise specified, terms such as “attached” or “connected” are intended to include integral connections, as well as connections between physically separate components.
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FIG. 1 is a schematic illustration of a rotary aircraft orrotorcraft 100 implementing arotor mast 110 configured in accordance with embodiments of the present technology. Therotorcraft 100 may include avehicle body 120, apower source 130 carried by thevehicle body 120, a rotor assembly 140 (which may include ahub 150 supporting one ormore rotor blades 160, such as two or more rotor blades 160), and therotor mast 110, which transfers rotation (torque) from thepower source 130 to therotor assembly 140 to rotate therotor assembly 140 to create thrust and/or lift. Thepower source 130 can include an engine, a transmission, and/or other suitable devices or mechanisms for rotating therotor mast 110 and therotor assembly 140. Therotorcraft 100 can include features that are conventional to rotorcraft 100 or other aircraft, in addition to implementing aspects of therotor mast 110 in accordance with embodiments of the present technology. -
FIG. 2 is a partially schematic side view of therotor mast 110, configured in accordance with embodiments of the present technology. Therotor mast 110 includes ashaft body 210 and at least one fitting attached to theshaft body 210. For example, therotor mast 110 may include afirst fitting 220, asecond fitting 230, and/or an inner race element 240 (which may be called a third fitting), each being attached to theshaft body 210. In some embodiments, thefirst fitting 220 may be configured to connect to the power source 130 (seeFIG. 1 ). For example, thefirst fitting 220 may include a gear and/or thefirst fitting 220 may be connected to a gear, such as a splined drive, a bull gear, a planetary carrier, and/or another gear or plurality of gears, and/or another suitable connection to thepower source 130. Thesecond fitting 230 may be configured to connect to the hub 150 (seeFIG. 1 ). The first andsecond fittings representative splines 250 are schematically illustrated inFIG. 2 ). Theinner race element 240 may be configured to mate with a bearing surface or other bearing device associated with therotorcraft 100, such as a portion of thepower source 130, for supporting therotor mast 110 in an aligned position while also allowing rotation of therotor mast 110. - The
shaft body 210 comprises composite material, such as composite laminate material. Theshaft body 210 may be formed by suitable composite manufacturing techniques. For example, in some embodiments, theshaft body 210 may be formed with a fiber placement process. The first andsecond fittings inner race element 240 may comprise metal material or another suitable material. Accordingly, therotor mast 110 may be called a hybrid rotor mast because it may include acomposite shaft body 210 attached to metal fittings. -
FIG. 3 is a partially schematic cross-sectional view of therotor mast 110, taken across the line labeled “FIG. 3 ” inFIG. 2 . Thefirst fitting 220 includes a first fitting interior opening 300 positioned and configured to receive theshaft body 210. Thesecond fitting 230 includes a second fittinginterior opening 310 positioned and configured to receive theshaft body 210. Theinner race element 240 also includes an inner race opening 320 positioned and configured to receive theshaft body 210. Theshaft body 210 may extend through theinner race element 240 and into each of thefittings shaft body 210 may not extend through the full length of either of thefittings rotor mast 110, specifically during curing of the composite forming theshaft body 210, theshaft body 210 expands outwardly relative to its longitudinal axis x to contour against the inner surfaces of thefittings inner race element 240. - In some embodiments, the
shaft body 210 may also be attached to thefittings adhesive material 330 positioned in one or more (such as all) of thefittings fittings shaft body 210. In some embodiments, the adhesive can include an epoxy film adhesive such asFM 300 or AF 163, or another adhesive suitable for facilitating bonding between thecomposite shaft body 210 and the material forming the fittings with shear strength characteristics and other characteristics suitable for use in rotorcraft or otherwise suitable for bonding composite material to metal material. In some implementations of embodiments of the present technology, it may be preferable to include theadhesive material 330 in order to provide redundancy to the connection between theshaft body 210 and the fitting(s) 220, 230, 240. However, in some embodiments, theadhesive material 330 is optional and may be omitted if such redundancy is not required or desired. -
FIG. 4 is a detailed view of a portion ofFIG. 3 (as indicated by the “FIG. 4 ” annotation inFIG. 3 ). To simplify the illustration inFIG. 4 , theadhesive material 330 is not shown inFIG. 4 . In some embodiments, aninterface 400 between thesecond fitting 230 and theshaft body 210 may be contoured along the longitudinal axis x. Contouring theinterface 400 along the longitudinal axis x provides a mechanical lock between thesecond fitting 230 and theshaft body 210, which complements theadhesive material 330. - To form the contour, the second fitting
interior opening 310 may include aninner surface 410 that may be contoured along the longitudinal axis x. Theinterface 400 may be formed by theshaft body 210 being expanded against theinner surface 410. Theinner surface 410 may include a firsttapered section 420 in which theinner surface 410 converges toward the longitudinal axis x, a secondtapered section 440 in which theinner surface 410 diverges away from the longitudinal axis x, and/or a non-tapered section 450 (extending parallel to the longitudinal axis x) positioned between the first and secondtapered sections tapered section 420 may be called a converging portion and the secondtapered section 440 may be called a diverging portion. In some embodiments, thenon-tapered section 450 may be an apex or transition point rather than a surface extending along the longitudinal axis x. - The one or more
tapered sections rotor mast 110 by resisting movement of the fitting 230 along the longitudinal axis x. For example, in some embodiments, the firsttapered section 420 carries axial loads opposite the positive thrust direction and the secondtapered section 440 carries axial loads in the positive thrust direction. The contouring of theinner surface 410 also carries moment loads (transverse to the x-axis) against theinterface 400 to support moment loads on theoverall rotor mast 110. - Although two tapered
sections FIG. 4 , in some embodiments, more or fewer tapered sections may be implemented, which may entail additionalnon-tapered sections 450 therebetween. Accordingly, theinner surface 410 may be contoured in other ways to lock the fitting 230 in position along the longitudinal axis x and to lock the fitting 230 against moment loads. - Although
FIG. 4 only shows thesecond fitting 230, in some embodiments, theinterior opening 300 of thefirst fitting 220 may include a similar configuration as theinterior opening 310 of thesecond fitting 230. For example, thefirst fitting 220 may include a converging taper, a diverging taper, and/or a non-tapered section between the converging taper and the diverging taper (FIG. 3 shows tapering of theopening 300 in thefirst fitting 220 similar to the tapering of theopening 310 in the second fitting 230). In other words, theinterface 400 shown inFIG. 4 may be implemented in thefirst fitting 220. Accordingly, thefirst fitting 220 may also interface with theshaft body 210 in a manner that facilitates support of axial and moment loads by therotor mast 110. -
FIG. 5 is a schematic cross-sectional view of portions ofFIGS. 2, 3 , and/or 4, as indicated by the “FIG. 5 ” indicator inFIGS. 2, 3, and 4 . To support torque loads (about the longitudinal axis x) between theshaft body 210 and thefirst fitting 220, thesecond fitting 230, and/or theinner race element 240, some or all of theinterface 500 between theshaft body 210 and thefittings non-tapered section 450 between thetapered sections 420, 440 (seeFIG. 4 ) may have a non-circular perimeter. Likewise, a non-tapered section between tapered sections in thefirst fitting 230 may have a non-circular perimeter. An inner perimeter of theinner race element 240 may have a non-circular perimeter. In some embodiments, the tapered sections of the fittings may have non-circular cross-sectional shapes. In other embodiments, the tapered sections may have circular cross-sectional shapes. - Because the
shaft body 210 is expanded to be contoured against the interior of the fittings, theshaft body 210 may also have a non-circular cross-sectional shape at theinterfaces 500. The engagement of the non-circular cross-sectional shapes of theshaft body 210 and the openings in the fittings facilitates transfer of torque between theshaft body 210 and the fittings. - In some embodiments, the non-circular interfaces 500 (and consequently, the non-circular perimeters of the openings within the fittings) have an elliptical shape. In some embodiments, the
non-circular interfaces 500 may have oval shapes, shapes having one or more lobes, and/or shapes having one or more recesses. Embodiments of the present technology may have other suitable non-circular shapes. - Rotor masts configured in accordance with embodiments of the present technology may be manufactured with existing manufacturing methods. For example, the composite tube (shaft body 210) may be laid up on a mandrel (such as an inner mold line mandrel). To prevent fiber distortion, it may be important to consolidate the composite material. A suitable method for consolidating the laminate material includes fiber placement composite fabrication. The composite tube (shaft body 210) may then be installed in an outer mold line tool along with the fittings. The mandrel may be removed and replaced with a bladder. The bladder may apply pressure to creep the composite material outwardly toward the fittings and the tool (i.e., to contour the composite material against the inner surfaces of the
fittings - One aspect of the method of making a rotor mast takes advantage of the difference in coefficients of thermal expansion between metal components and composite components. While curing with heat, the metal components expand more than the composite components (which creep as the resin flows), and the composite material flows to meet the contour of the metal. When the assembly cools, the metal components clamp the composite with hoop compression. If a designer or operator wants to reduce (for example, minimize) or further control the hoop compression, the shaft assembly may include an optional plug element 655 (shown in
FIG. 4 , for example) temporarily or permanently positioned in the composite tube (shaft body 210) to support the composite tube (shaft body 210) during curing. Theoptional plug element 655 may be used to prevent thecomposite tube 210 from being pulled from the fitting during curing or after curing. However, in some embodiments, theplug element 655 may be omitted. - Advantages of the present technology include reduced weight, improved strength, and improved corrosion resistance relative to conventional rotor masts. Embodiments of the present technology also provide redundancies in the connection between the
composite shaft body 210 and the metal components. For example, torque loads about the x-axis (which rotate therotor assembly 140, for example) may be supported by the non-circular interfaces between theshaft body 210 and thefittings shaft body 210 and the fittings (for example, the tapered sections), supports axial and moment loads. The adhesive may further assist the mechanical bond formed by the contouring. - From the foregoing, it will be appreciated that some embodiments of the present technology have been described herein for purposes of illustration, but various modifications may be made without deviating from the disclosed technology. For example, the
rotor mast 110 may include more or fewer fittings or bearing components. Although “rotor masts” are described, the technology described herein can be used to make other shaft assemblies, including other shaft assemblies for transferring rotation from a power source to a hub, such as propeller shafts for airplanes. - Further, while advantages associated with some embodiments of the technology have been described in the context of those embodiments, some embodiments may also exhibit said advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the present technology. Accordingly, the present disclosure and associated technology may encompass other embodiments not expressly described or shown herein.
Claims (16)
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US17/580,392 US11718391B2 (en) | 2021-03-23 | 2022-01-20 | Rotary aircraft hybrid rotor mast |
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US202163164884P | 2021-03-23 | 2021-03-23 | |
US17/580,392 US11718391B2 (en) | 2021-03-23 | 2022-01-20 | Rotary aircraft hybrid rotor mast |
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US20220324557A1 true US20220324557A1 (en) | 2022-10-13 |
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US20100166568A1 (en) * | 2006-08-17 | 2010-07-01 | Lin Sherman S | Composite-Steel Hybrid Mast for Rotorcraft |
US20140377073A1 (en) * | 2013-06-25 | 2014-12-25 | The Boeing Company | Systems and methods for blade attachment |
US9821520B2 (en) * | 2015-03-19 | 2017-11-21 | Bell Helicopter Textron Inc. | Hybrid composite-metal shaft |
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FR2285298A1 (en) * | 1974-09-19 | 1976-04-16 | Aerospatiale | TAIL ROTOR ARRANGEMENT FOR GIRAVIONS |
IT1161532B (en) * | 1983-10-26 | 1987-03-18 | Agusta Aeronaut Costr | STEEL TUBULAR TRANSMISSION SHAFT |
US7665969B2 (en) * | 2005-01-24 | 2010-02-23 | Bell Helicopter Textron Inc. | Assembly for providing flexure to blade system |
US10017247B1 (en) | 2017-06-02 | 2018-07-10 | Bell Helicopter Textron Inc. | Rotor mast assembly |
US11001369B2 (en) * | 2018-04-02 | 2021-05-11 | Bell Helicopter Textron Inc. | Hybrid light weight rotorcraft hub trunnions |
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2022
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Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100166568A1 (en) * | 2006-08-17 | 2010-07-01 | Lin Sherman S | Composite-Steel Hybrid Mast for Rotorcraft |
US20140377073A1 (en) * | 2013-06-25 | 2014-12-25 | The Boeing Company | Systems and methods for blade attachment |
US9821520B2 (en) * | 2015-03-19 | 2017-11-21 | Bell Helicopter Textron Inc. | Hybrid composite-metal shaft |
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US11718391B2 (en) | 2023-08-08 |
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